Trainer calibration question

I have a Tacx Vortex wheel on trainer, and carried out a calibration check (after a fw update of the tacx app… not sure if that is coincidental) and it has adjusted the resistance grading by a massive amount. I’ve gone from avaraging 240w on the flat to barely being able to push 150w. Im happy that the original setting was reasonably correct, my measured FTP on a stages bike was 235w. Ive retried the calibration a number of times and it stays the same. I cannot get anywhere near my previous PBs and now lag miles back on club group events, very frustrating. Is there any way to correct this and get back to my previous setting?

Are you using the Tacx app to calibrate your trainer? Don’t use the Zwift calibration function.

Hi I have a Tacx Bushido wheel on trainer and found the same thng. It appeared to be reading too low. I borrowed a friends power meter pedals and this confirmed my suspicions.
Have a look at the following video and this will explain what is going on and how to correct the trainer output. After a few attemps I managed to match the output of the trainer to the power meter.
Hope this helps.